The present invention relates to control circuits for steering a motorized wheelchair.
A typical motorized wheelchair will have a right drive motor for the right wheel and a left drive motor for the left wheel. The wheelchair can be steered by applying more power to the right motor or the left motor, respectively. This is typically done with a joystick control which is coupled to a pair of potentiometers. Each potentiometer provides an input to an amplification and drive circuit to drive the respective motors. When the joystick is moved to the right, for instance, the signal from the right potentiometer will increase while the signal on the left potentiometer will decrease. For sharp turns, in fact, one motor may be put into reverse. Thus, for instance, for a sharp right turn, the left motor will have a large forward power applied while the right motor will be put slightly into reverse.
This mechanism for turning a wheelchair causes difficulty when one is trying to steer a wheelchair in a straight line. This difficulty arises because a slight movement to the side with the joystick will tend to put the wheelchair into a turn, thereby making it move erratically. This is particularly difficult for the handicapped who do not have sufficient motor control to accurately move the joystick. There is thus a need for a control circuit which can provide turning signals to the drive motors while allowing the wheelchair to be driven in a straight line without requiring precise joystick control.